This invention relates to compositions for controlled release of biologically active materials. More specifically, it relates to polyhydroxy polymer/salt compositions with biologically active materials contained within a matrix.
The compositions of the present invention are particularly useful for the prolonged delivery of herbicides and other pesticides by granular application to the soil. As such they decrease the loss of active ingredients.
It is known that polyhydroxy polymers such as polyvinyl alcohols (PVA) can be coagulated from aqueous systems by the addition of various salts. An application of this fact can be found in French Patent 1,304,891, which describes a process for converting PVA into microcapsules by treating PVA dye emulsions with inorganic sulfates.
U.S. Pat. No. 4,382,813 describes the coagulation or precipitation of an entrapped pesticidal agent by the rapid insolubilization of a starch alkoxide containing material with a bivalent cation selected from the group of calcium, barium, and strontium. These systems are limited to materials having low solubility in water and result in a strongly basic matrix and are not applicable to alkali sensitive materials.
No prior art was found that discloses the present invention.